Evaluation of Alternative Decommissioning Criteria for DD of Buildings Using Conventional Dose and Risk Assessment Techniques

摘要

The paper illustrates the application of methodologies for demonstrating that alternative decommissioning levels, in excess of traditional surface decontamination criteria, that can safely be used to guide demolition without a negative impact on public health or the environment. This approach also can result in significant cost savings and minimize risk to workers performing decontamination activities. Decommissioning and demolition (D&D) projects nationwide are well underway with characterization andpre demolition planning. A key concept emerging from many projects that can be important to the efficient and successful decommissioning is the use of dose and risk based rationale to define acceptable residual radionuclide concentrations and to evaluate the suitability of concrete and other demolition materials as backfill. The experiences from an existing project at the Rocky Flats Environmental Technology Site are used to demonstrate methodologies and regulatory and technical rationale for establishing alternative decontamination levels that are suitably safe criteria for application to decommissioning of radiologically contaminated buildings. This will be accomplished by demonstrating the dose and risk impacts associated with: a) actual demolition and b) placement of concrete building materials using conventional, accepted regulatory assessment techniques. It is generally known that traditional "free release " criteria and RADCONpractices are based largely on instrument and operational capabilities and are not dose or risk based. The findings demonstrate that dose and risk based decommissioning guidelines can be derived that are well in excess of the more traditional use of free release criteria and conventional RADCON practices. In the case of Building 371/374, in spite of the implications of this analysis, all demolition was ultimately conducted as conventional radiological operations and materials whose concentrations exceed conventional free release criteria were never accessible to the public. The reason that the dose and risk based alternative criteria were not employed was based on risk management decision factors including requirements to obtain approval of alternative levels, project timing, and other intangibles.